diff --git a/apps/opencs/model/doc/savingstages.cpp b/apps/opencs/model/doc/savingstages.cpp
index ee65248e2f..6a03301806 100644
--- a/apps/opencs/model/doc/savingstages.cpp
+++ b/apps/opencs/model/doc/savingstages.cpp
@@ -321,6 +321,10 @@ void CSMDoc::WriteCellCollectionStage::perform (int stage, Messages& messages)
                 {
                     CSMWorld::CellRef refRecord = ref.get();
 
+                    // Correct content file number to be relative to plugin
+                    refRecord.mRefNum.mContentFile = mDocument.getData().getPluginContentFile(
+                        refRecord.mRefNum.mContentFile);
+
                     // recalculate the ref's cell location
                     std::ostringstream stream;
                     if (!interior)
diff --git a/apps/opencs/model/world/data.cpp b/apps/opencs/model/world/data.cpp
index 8b0a9b384d..8347cd5bc3 100644
--- a/apps/opencs/model/world/data.cpp
+++ b/apps/opencs/model/world/data.cpp
@@ -902,6 +902,8 @@ int CSMWorld::Data::startLoading (const boost::filesystem::path& path, bool base
     mReader->setIndex(mReaderIndex++);
     mReader->open (path.string());
 
+    mContentFileNames.insert(std::make_pair(path.filename().string(), mReader->getIndex()));
+
     mBase = base;
     mProject = project;
 
@@ -914,6 +916,35 @@ int CSMWorld::Data::startLoading (const boost::filesystem::path& path, bool base
         mMetaData.setRecord (0, Record<MetaData> (RecordBase::State_ModifiedOnly, 0, &metaData));
     }
 
+    // Fix uninitialized master data index
+    for (std::vector<ESM::Header::MasterData>::const_iterator masterData = mReader->getGameFiles().begin();
+        masterData != mReader->getGameFiles().end(); ++masterData)
+    {
+        std::map<std::string, int>::iterator nameResult = mContentFileNames.find(masterData->name);
+        if (nameResult != mContentFileNames.end())
+        {
+            ESM::Header::MasterData& hackedMasterData = const_cast<ESM::Header::MasterData&>(*masterData);
+            hackedMasterData.index = nameResult->second;
+        }
+    }
+
+    // Needed for saving
+    if (!mBase)
+    {
+        mReverseContentFiles.insert(std::make_pair(mReader->getIndex(), 0));
+    }
+    if (mProject)
+    {
+        mReverseContentFiles.insert(std::make_pair(mReader->getIndex(), 0));
+
+        // A new project has no header, so extrapolate the content files from the reader index
+        // The base/project index of 0 will not be overwritten
+        for (int i = 0; i < mReader->getIndex(); ++i)
+        {
+            mReverseContentFiles.insert(std::make_pair(i, i+1));
+        }
+    }
+
     return mReader->getRecordCount();
 }
 
@@ -1171,6 +1202,16 @@ int CSMWorld::Data::count (RecordBase::State state) const
         count (state, mPathgrids);
 }
 
+int CSMWorld::Data::getPluginContentFile(int currentContentFile)
+{
+    std::map<int, int>::iterator searchResult = mReverseContentFiles.find(currentContentFile);
+
+    if (searchResult != mReverseContentFiles.end())
+        return searchResult->second;
+    else
+        return 0; // Assume faulty plugin with original content
+}
+
 std::vector<std::string> CSMWorld::Data::getIds (bool listDeleted) const
 {
     std::vector<std::string> ids;
diff --git a/apps/opencs/model/world/data.hpp b/apps/opencs/model/world/data.hpp
index f0c3dcd417..8fc68b9f7e 100644
--- a/apps/opencs/model/world/data.hpp
+++ b/apps/opencs/model/world/data.hpp
@@ -123,6 +123,10 @@ namespace CSMWorld
 
             std::vector<boost::shared_ptr<ESM::ESMReader> > mReaders;
 
+            std::map<std::string, int> mContentFileNames;
+            // current index, plugin index
+            std::map<int, int> mReverseContentFiles;
+
             // not implemented
             Data (const Data&);
             Data& operator= (const Data&);
@@ -298,6 +302,9 @@ namespace CSMWorld
             int count (RecordBase::State state) const;
             ///< Return number of top-level records with the given \a state.
 
+            /// Returns the content file number relative to the plugin being edited, 0 by default
+            int getPluginContentFile(int currentContentFile);
+
         signals:
 
             void idListChanged();